Research Summary

Professor Fish’s area of research interest is the ecology of vector-borne pathogens. Recent emphasis has been on tick-borne pathogens causing Lyme disease, human anaplasmosis and babesiosis, and on mosquito-borne West Nile virus and dengue fever. Current projects include experimental manipulation of natural transmission cycles, vaccination of wildlife reservoirs against vectors and vector-borne pathogens, interactions among multiple pathogens in vectors and hosts, vector competence for viral and bacterial pathogens, and pathogen population genetics. Spatial analysis of pathogen prevalence using satellite imagery and geographic information systems forms the basis for applied studies in landscape epidemiology. His laboratory maintains colonies of ticks and mosquitoes for experimental studies, and a network of field sites is available for ecological studies. Prof. Fish is Director of the Yale Center for EcoEpidemiology, an interdisciplinary center that seeks to integrate environmental science and ecology with medical epidemiology. He is also on the Steering Committee of the Yale Climate and Energy Institute where he coordinates campus wide research on climate and human health.

Extensive Research Description

Professor Fish’s interests in entomology and evolutionary ecology form the basis for his approach to studying epidemiology and prevention of vector-borne disease. His early interest in the community ecology of mosquito-dominated aquatic habitats led to discoveries of resource partitioning and feeding behavior of mosquito larvae inhabiting pitcher plants, bromeliads and tree-holes. He studied the ecology of the tree-hole inhabiting Aedes triseriatus mosquito on an NIH Postdoctoral Fellowship with George B. Craig Jr. at the University of Notre Dame. A fatal case of LaCrosse viral encephalitis transmitted by Aedes triseriatus led to his establishment of the first mosquito and arbovirus surveillance program in Westchester County, NY, which he directed for four years while at Fordham University.

His interests in mosquitoes and mosquito-borne disease were set aside in 1982 with the discovery of Borrelia burgdorferi, the bacterial agent of tick-borne Lyme disease. This new disease quickly became epidemic in Westchester County and suburban New York City, where he conducted basic studies on the distribution and abundance of the tick vector Ixodes scapularis. These studies showed how this tick species was rapidly expanding its range into new areas and causing the spread of Lyme disease. Studies on risk assessment demonstrated the peridomestic nature of Lyme disease and described the landscape epidemiology of Lyme disease. Collaboration with NASA’s Ames Research Center refined the landscape epidemiology approach and demonstrated the application of satellite imagery and geographic information systems in vector-borne disease epidemiology. This work culminated in the production of the National Lyme Disease Risk Map for the CDC, which was used in the Recommendations for the Use of Lyme Disease Vaccine by the Advisory Committee on Immunization Practices.

The Lyme Disease Risk Map was revised in 2004 with the largest field study ever conducted on ticks in the US. Funded by the CDC, the project involved the participation of more than 100 research assistants and students who collected ticks from more than 400 locations throughout the range of Ixodes scapularis (cited as one of the 10 worst jobs in science by Popular Science Magazine). All ticks were assessed for the prevalence of Borrelia burgdorferi, which was also genotyped. Satellite imagery and climate data were used to create a spatial model for predicting the distribution of infected ticks at a resolution of 10 km.

This information combined with information on tick identification and removal, assessment of feeding duration, and Lyme disease symptoms for the first smart phone app on vector-borne disease prevention. Designed for the iPhone, the app accurately determines if infected ticks occur at the user location and advises the user of appropriate actions to take to minimize the risk of acquiring Lyme disease.

Other research on tick-borne disease included a genetic study on the evolution and spread of Borrelia burgdorferi in North America, control of Ixodes scapularis populations in the northeastern US through topical application of acaricide to white-tailed deer, reduction of B. burgdorferi infection prevalence in I. scapularis through field vaccination of the rodent reservoir host Peromyscus leucopus, the discovery of a new tick-borne pathogen, Borrelia miyamotoi in I. scapularis and description of the first clinical cases of human infection with B. miyamotoi. A laboratory colony of I. scapularis ticks and of Peromyscus leucopus mice facilitated the maintenance of natural cycles of these and other tick-borne pathogens, including Anaplasma phagocytophilum and Babesia microti . Studies on pathogen interactions in ticks and mice revealed both positive and negative effects at both the species and genotype level.

Fish and his students studied West Nile virus during the 1999 epidemic in New York City where it was first introduced into the Western Hemisphere. Working with the Wildlife Conservation Society, a mosquito and arbovirus surveillance program was quickly established at the Bronx Zoo where mosquito abundance data and virus isolations from mosquitoes focused mosquito control activities to minimize environmental impact. Other studies on West Nile virus identified the initial outbreak area in NYC and described the spread of West Nile virus in the Northeastern US.

Studies on dengue fever began in 2004 after Fish and his students conducted a mosquito survey on the island nation of Dominica in the Lesser Antilles. A Medical Entomology Laboratory was established and the Ministry of Health hosted student internships for studies on dengue fever epidemiology and surveillance of the mosquito vector Aedes aegypti.Fish was called upon to assist Dominica with their outbreak of chikungunya virus in 2014. He led a futile attempt to control the epidemic through patient isolation in bed nets and indoor residual spraying of infected residences. This experience was useful in understanding control efforts for Zika epidemics.

His current projects include a study on the mosquitoes and arboviruses of the Greater Florida Everglades Region and the potential impacts of climate change and wetlands restoration upon arboviral disease emergence in South Florida. He has established a research laboratory at Big Cypress National Preserve in collaboration with the National Park Service. He is also involved in studies on the ecological role of mosquitoes and arboviruses in wetland ecosystems and in ways to manage wetlands to minimize adverse impacts upon wildlife and human health.

Activities

Chikungunya Outbreak in Dominica
Dominica (2014)

Working with public health officials in Dominica to try to understand what happened, after efforts to contain the virus by isolating febrile patients from mosquitoes with bed nets so they could not infect mosquitoes, and also treating houses with insecticide to kill any mosquitoes that the patient...

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